Known field devices can be technical devices in an automation industry which are in a direct relationship with a production process. Such field devices can be both actuators, such as actuating elements or valves, and sensors, such as measuring transducers, in factory and process automation. The field devices can be connected to a superordinate control system, usually via a fieldbus, with the aid of a connection line. By means of this connection, data can be interchanged and then used for regulation, control and further processing. Frequently used communications standards for fieldbuses are CAN, HART, PROFIBUS or can also be formed on the basis of ETHERNET, Profinet, IP.
Furthermore, these field devices, such as 4-20 mA devices, but also those with a fieldbus, can be supplied energy via this connection line.
In some instances, the connection line is not routed directly from the respective field device to the control component, but initially individually from the respective field device to a field device connection unit, which is then connected to the control component by a trunk cable, such as a bus cable. DE 101 35 980 C1 discloses an arrangement for connecting field devices arranged decentrally and in the immediate vicinity of the process to a remote, central device in an automation installation with a distribution board which has at least one communications interface for communicating with the remote, central device, a plurality of pluggable input/output modules and a multi-pole terminal panel for connecting the field devices. The input/output modules have a system-side communications interface and a field-side communications interface in the same plug-in plane. The system-side communications interfaces of the I/O modules are connected to the communications interface for communication with the central device. The field-side communications interfaces of the I/O modules and the terminal panel are connected to contacts of a plug-type contact apparatus which are separate from one another.
In this case, a configuration-determining plug-in unit is provided which has a mating plug-in contact apparatus corresponding to the plug-in contact apparatus and conductor links for electrically connecting contacts, which are separate from one another, of the plug-in contact apparatus in such a way that in each case one field device is connected to the field-side communications interface of at least one I/O module. Erroneous assignments of the device with incorrect configuration-determining plug-in units can in this case result in serious faults in the field device connection unit.